Please bear with me here - I'm pretty new to GIS, and I'm having a lot of confusion about all the different terms I've seen thrown around.

Here's my problem: I have a large dataset of point features, all within a arbitrary geographical area (in this case, the greater San Francisco Bay Area). The point features have no other information besides lat/long.

What I want to do is display them in such a way that I can easily see concentrations. I think what I'm looking for is called a heatmap, although I've also seen things like "kernel density", "point density" and other terms.

The base of my map is several layers I got from a large dataset. That means that I don't really have a polygon layer that is just the area I'm looking at - the main layer is a polygon feature class of counties in the Western United States. I could extract just the counties I'm interested in if that would make this process easier.

I'm looking for something like the images in dkwiens' post in this thread.

What do I need to do? The simpler the explanation, the better - I've spent quite a while on Google looking for this, and while I've found a lot of stuff that seems like it's what I want to do, I haven't been able to translate it to my problem.

Edit: I should mention that I think the closest I've gotten is with the point density tool. I set the "input point features" to the layer containing my points, the "Population" field to NONE (the other options are X and Y), and a cell size of 50. I've tried several values of Radius, both in map units and in cell units (whatever that means!). After running the tool, I get a layer that looks like the attached screenshot. But nothing actually shows up on the map.
Here's the screenshot: http://i41.tinypic.com/35n7itu.jpg

Edit2: I noticed that when I look at the generated "File GeoDatabase Raster Dataset" in ArcCatalog, the preview tab has nothing in it - just a blank white screen. Not sure if it's supposed to be like that or not.

Maybe? I'm not sure if that's the right tool. I've tried it, and I get a similar result as the screenshot of the result of the point density tool - it creates a new layer, but nothing shows on the map.
–
Isaac Dontje LindellApr 28 '13 at 16:38

Try creating a population/count field and put a value of 1 for each feature, then run the tool.
–
artwork21Apr 28 '13 at 16:39

Same result - a new layer but nothing added to the map. Based on my reading of the docs, a population field should not be necessary anyway. If the Population option is set to None, it will just count each point once (which is what I want).
–
Isaac Dontje LindellApr 28 '13 at 16:50

Check that your point data should be defined in a projected coordinate system and not a geographic one.
–
artwork21Apr 28 '13 at 17:14